The bonding of the two rigid parts of thermoplastic materials through thermocompression is published in Soo Hyun Lee et al “A polymer lab-on-a-chip for reverse transcription (RT)-PCR based point-of-care clinical diagnostics”, The Royal Society of Chemistry 2008, Lab Chip, 2008, 8, 2121-2127. By using two rigid and thick parts (around one millimeter), in the case of requiring the heating of liquids or gases inside the device, from an element located outside the fluidic structure, this is hindered as it has to go through a low thermal conductivity plastic material, which is considerably thick (several hundreds of micrometers). Also, there are not parts which can be moved for their use as fluidic control elements (valves, pumps, . . . ) for the same reason.
When one of the two thermoplastic parts to be bonded is less than 200 micron thick (sheet) the bonding process through thermocompression causes the permanent deformation of the sheet, preventing the fabrication of the device with a flat finishing surface. The temperatures required for the permanent bonding between the sheet and the thermoplastic part causes said deformation. The deformation of said membrane is counterproductive for many applications (lack of dimensional reproducibility, poor heat transmission due to a bad contact with the heating element, creating of bubbles in the case of being used for the fabrication of microfluidic chips, inappropriate transmission of an optical signal due to the curvature of the membrane sealing a possible reaction chamber, etc.).
The bonding of the two rigid parts of thermoplastic materials through solvent is published in Brown L et al. “Fabrication and characterization of poly(methylmethacrylate) microfluidic devices bonded using surface modifications and solvents”, The Royal Society of Chemistry, 2006, Lab Chip 6, 66-73. The parts used are rigid and thick and the dissolution used is applied on the microfabricated structure. Then, it is necessary to align the parts and submit them to pressure and temperature for 30 minutes, followed by a cooling ramp. The fabrication method and characteristics of the substrates do not allow parts which can be moved.